Pic. 8.82. Self-diagnosis function start circuit
The air conditioner control unit has a self-diagnosis function. Information about malfunctions in the air conditioning system is stored in the system memory in the form of fault codes. Using the buttons on the air conditioner control panel, you can display the fault codes stored in the memory (see fig. 8.82 and tab. 8.5). Since the system memory that stores fault codes is powered by a battery, fault codes are stored even when the ignition is turned off.